Why is the Check Engine Light On?

Why is the Check Engine Light On?There is one thing that many drivers are scared of that doesn't have to do with getting a ticket or being involved in a car accident. The check engine light is something that has the ability to strike fear into those who see it. Unfortunately there is a big misconception about what this light is really trying to tell you. Chances are that illumination of this light is reflecting a small issue, such as a malfunctioning sensor. But if you don't have diagnostics ran soon it could result in a much bigger problem occurring, as demonstrated by this first check engine light issue.

Failed Catalytic Converter

The catalytic converter is one of the most expensive parts on your car. It is tasked with converting hazardous exhaust fumes into less harmful emissions. It is very difficult for it to fail on its own, so should it be found to be having trouble during a check engine light diagnostic, chances are that the light has been on for some time, and another, much smaller problem originally triggered it. Always be sure to have diagnostics ran as soon as the light comes on.

Exhaust Leak

A fairly common issue that will trigger the light is an exhaust leak. This is because a leak generally throws off the readings of the oxygen sensor off. This will result in your vehicle running rich, meaning using too much gasoline because the o2 sensor helps to dictate the proper air/fuel mix used by the engine.


Misfiring means that the spark plugs are not firing at the correct time, resulting in a poor running engine and a huge waste of fuel. Spark plugs are relatively simple to change on most vehicles, making fixing this problem a breeze.

Faulty MAF sensor

The mass airflow sensor detects how much air is coming into the engine and calculates how much of it needs to be mixed with the gasoline in order to create a proper running engine. A malfunctioning MAF sensor often results in a rich running vehicle.

Malfunctioning or Loose Gas Cap

When you fill up be sure to always tighten the gas cap before leaving the station, as a loose cap, or a broken one for that matter can trigger the light. This will happen because gas vapors will evaporate out of the filler hose, thus causing a waste of gas.

If your check engine light has come on don't delay having diagnostics ran to find out what the issue is. For check engine light repair in Westminster, CO, head to All Engines & Transmissions. We specialize in used and rebuilt engines and transmissions, but we offer complete diagnostics and auto repair. Give us a call at (720) 707-0183 to schedule an appointment or to learn more about our Westminster auto repair shop.

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Written and Published By MORBiZ